Featured Research

from universities, journals, and other organizations

Tissue Engineering Could Become New Coronary Bypass

Date:
November 15, 2001
Source:
University Of Michigan
Summary:
A spongy plastic material impregnated with two kinds of growth factor has been shown to encourage the formation of healthy new blood vessels in living rats, according to a tissue engineering research team at the University of Michigan.

ANN ARBOR --- A spongy plastic material impregnated with two kinds of growth factor has been shown to encourage the formation of healthy new blood vessels in living rats, according to a tissue engineering research team at the University of Michigan.

The ability to grow new blood vessels in a controlled fashion could lead to better treatments for coronary artery disease, to speed wound healing, or to help diabetic patients who are suffering from peripheral vascular disease.

"This new approach allows us to deliver a controlled dose of growth factors to a specific tissue," said David J. Mooney, a professor of biologic and materials science in U-M's College of Engineering and School of Dentistry. "To grow a replacement tissue cell by cell, you need a combination of growth factors delivered in the right sequence at the proper time and in the right place. Just injecting a large amount of it with a needle doesn't work."

Coronary artery disease occurs when blocked vessels fail to deliver enough blood and oxygen to the heart muscle itself. The coronary bypass operation, which is performed nearly 3 million times per year in the United States, involves removing an artery or vein from one part of the body and then stitching it onto the threatened area of the heart. The ribcage must be cut open, and the heart's beating is stopped during the procedure.

However, this polymer may be able to grow new vessels on site with much less invasive surgery.

Two naturally-occurring growth factor chemicals are key to the formation of proper blood vessels, VEGF, the Vascular Endothelial Growth Factor, and PDGF, the Platelet-Derived Growth Factor. But simply basting an area of tissue with both chemicals does not result in satisfactory angiogenesis, or vessel development. The vessels may form, but they end up falling apart because they are not constructed properly. And if VEGF levels fall too low, vessels are even subject to "pruning and remodeling," the researchers report.

The new polymer formulation combines proper doses of VEGF and PDGF in a way that encourages the proper structure of vessels and guides their growth for weeks. It was developed in Mooney's labs at the School of Dentistry and the College of Engineering with graduate students Thomas P. Richardson, Martin C. Peters and Alessandra B. Ennett, and was reported in the November 2001 edition of Nature Biotechnology.

In the polymer, VEGF starts the process of angiogenesis and recruits the endothelial cells which line blood vessels. PDGF then recruits smooth muscle cells to form the resilient outer layer of the artery or vein. Only with the two chemicals working together in appropriate doses do robust vessels develop. The U-M team hit on a way to release VEGF from the polymer immediately in the first few days after implantation, and then to slowly release measured doses of PDGF by using microcapsules that dissolve over time. The polymer itself will also melt away over time.

"The polymer might be used as a heart patch," Mooney said. "You'd lay a sheet of it on the muscle and it could encourage the formation of a lot of vessels through it and around it."

To test the polymer, the researchers implanted four different versions of the material under the skin on the backs of laboratory rats. One polymer held just VEGF, one just PDGF, one had both with the PDGF in time-release microcapsules, and one was just the semi-porous polymer without any added growth factors.

The VEGF by itself led to a dramatic increase in vessel formation, but the vessels were smaller than normal and were missing some of the cell types they needed to function well. PDGF by itself did not lead to any appreciable difference in the formation of blood vessels, though the existing vessels around the polymer did appear to grow larger in the presence of the growth factor.

Together, however, the growth factors created new blood vessels that were large and well-formed.

Though polymer "scaffolds" have been used in a variety of tissue engineering experiments, this is the first time multiple growth factors have been incorporated for release in a controlled-dose fashion. Mooney is confident his team will be able to impregnate a polymer with several growth factors and to release them in a timed fashion.

This new ability to deliver multiple growth factors in a controlled way has applications to many other kinds of tissue engineering beyond angiogenesis, Mooney said, since tissue formation probably rarely relies on just a single chemical signal.

###

On the Web:

David J. Mooney's Research, http://www.engin.umich.edu/dept/che/research/mooney/.

Biomedical Engineering Department, http://www.bme.umich.edu/


Story Source:

The above story is based on materials provided by University Of Michigan. Note: Materials may be edited for content and length.


Cite This Page:

University Of Michigan. "Tissue Engineering Could Become New Coronary Bypass." ScienceDaily. ScienceDaily, 15 November 2001. <www.sciencedaily.com/releases/2001/11/011115071858.htm>.
University Of Michigan. (2001, November 15). Tissue Engineering Could Become New Coronary Bypass. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2001/11/011115071858.htm
University Of Michigan. "Tissue Engineering Could Become New Coronary Bypass." ScienceDaily. www.sciencedaily.com/releases/2001/11/011115071858.htm (accessed July 31, 2014).

Share This




More Health & Medicine News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Health Insurers' Profits Slide

Health Insurers' Profits Slide

Reuters - Business Video Online (July 30, 2014) Obamacare-related costs were said to be behind the profit plunge at Wellpoint and Humana, but Wellpoint sees the new exchanges boosting its earnings for the full year. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
Peace Corps Pulls Workers From W. Africa Over Ebola Fears

Peace Corps Pulls Workers From W. Africa Over Ebola Fears

Newsy (July 30, 2014) The Peace Corps is one of several U.S.-based organizations to pull workers out of West Africa because of the Ebola outbreak. Video provided by Newsy
Powered by NewsLook.com
Weather Kills 2K A Year, But Storms Aren't The Main Offender

Weather Kills 2K A Year, But Storms Aren't The Main Offender

Newsy (July 30, 2014) Health officials say 2,000 deaths occur each year in the U.S. due to weather, but it's excessive heat and cold that claim the most lives. Video provided by Newsy
Powered by NewsLook.com
Concern Grows Over Worsening Ebola Crisis

Concern Grows Over Worsening Ebola Crisis

AFP (July 30, 2014) Pan-African airline ASKY has suspended all flights to and from the capitals of Liberia and Sierra Leone amid the worsening Ebola health crisis, which has so far caused 672 deaths in Guinea, Liberia and Sierra Leone. Duration: 00:43 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile: iPhone Android Web
    Follow: Facebook Twitter Google+
    Subscribe: RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins